A Hypothesis on Empty
by 221Bme
Summary: Sherlock gets a Fitbit. It's an experiment. But what exactly does that mean? (I know this isn't my best, and I'm so sorry... I can't seem to get it right at the moment, but I liked the idea...) (Eating disordered Sherlock)
1. An Experiment

"What's that, then?"

"Hm...?" Sherlock finally looked up from checking his new watch—or at least, what had first appeared to be a watch, but John had begun to notice over the course of the last hour or two that it seemed to be a lot more technical than that.

"You've checked it at least five times this morning. Looks like one of those... y'know..."

"Fitbits?" Sherlock supplied easily, glancing over at his friend, who was seated in his armchair, hair still ruffled from sleep. "That's because it is. I got it yesterday."

"The hell do you need an activity tracker for?" John frowned slightly.

Sherlock just gave him a look and paced over to the living room table, sorting through some of the piles of stuff. "It's an experiment."

"An... experiment?"

" _Yes._ " He turned his intense gaze on John yet again. "A scientific enquiry? A set of circumstances set up solely to prove or disprove a hypothesis? A way of—"

" _I know what an experiment is, Sherlock._ I just... don't see what you could possibly be trying to prove..."

"I'm... curious." The consulting detective paused a moment, his eyes straying to the sleek black band around his wrist again. "I know how the body functions, how much energy it should expend, exactly what it requires... but I thought it would be... _fun_ to see that in action. I have a body after all, even if it _is_ mostly just to carry my brain around, but that's beside the point."

"O...kay..." John nodded slowly, reaching for the cup of coffee he had forgotten about on the table beside him.

 _Cold, now..._

 _Wait..._

John stopped, with the cup still raised to his lips. "Was this... in any way inspired by that case we had last week? Y'know, the one with the guy who, em... the one who was killed by being starved to death?"

"Might have been..."

"You're not going to do that, right...?"

Sherlock rolled his eyes, letting out a heavy sigh. "Obviously, I'm not. I'm just curious. Don't be _absurd_."

"Alright, alright... just asking..." John made a face as he tried another sip of his cold coffee, knowing full well that it would be awful. "Fancy another case, then?"

" _Starving_ for one."


	2. Exhaustion

A little over two weeks had passed, bringing with them a few cases, the last of which proved to be the most time consuming and tiring.

John himself had to admit he was feeling its effects, as Sherlock had woken him that morning before the sun had even risen, pulling on his coat and gloves and talking excitedly about how he'd just figured it out—something about how it 'had to have been the cousin, because the victim didn't like chocolate.' Which of course made no sense at all to John, _especially_ with his mind still clouded with sleep.

He may or may not have growled at Sherlock to "go shove it."

Sherlock had just smirked and informed him that he'd be downstairs, and to take his time, as long as that time was no longer than five minutes.

Now, as they were just on their way home again, he could feel a yawn trying to force itself from him, and he clamped his lips together firmly in an attempt to stifle it. It was only 10:34, after all...

He knew precisely, because he could see the time displayed in white numbers on the face of Sherlock's Fitbit, upside down from where John was sitting beside him in the cab. The consulting detective had his head leaned back against the seat and his eyes closed, a position he hadn't moved from since they'd got in.

 _He was still wearing it..._

The cab pulled up in front of 221B, and John paid the driver and got out, shivering in the chill morning air. He glanced behind him, a bit surprised that Sherlock wasn't already on the doorstep, and was instead only just opening his eyes.

John frowned. "You coming?"

"Mm... yeah... 'course..."

As soon as they were inside Sherlock went directly to the sofa and let himself collapse onto it with a groan, not bothering to take off his coat, scarf, or gloves, or even kick off his shoes.

"I take it you're tired, then." John just stood in the centre of the living room for a minute, arms crossed and eyebrows raised.

" _Clearly..._ " He mumbled into the sofa cushions, still not moving.

"You know, you could probably avoid that problem by _sleeping_. I know it seems weird, but you should try it some time."

" _Very funny..._ "

John sighed, shaking his head. "I mean it, though... you keep pushing yourself like this, and it's no wonder you get to a point where you actually _can't_ anymore. It's not healthy."

Sherlock scoffed out loud—though it was muffled by the cushions. "Honestly... when have I ever been the poster child for 'health?'"

John rolled his eyes and walked over to the kitchen. "You could probably do with something to eat. It'll help. I'm hungry, anyway..."

There was no answer from the sofa, and John glanced back to the living room.

"Sherlock?"

When there was still no reply he shrugged, and set about making some toast.

 _Must have fallen asleep..._

 _Probably a good thing, anyway._

 _He'd been looking a bit pale recently..._


	3. Black, No Sugar

Early morning sunlight streamed through the front windows of the flat, catching tiny particles of dust in its golden hues as they floated slowly down toward the floor.

Everything was comfortably quiet, save for the soft bubbling of the kettle.

John cast another look at the book he'd been reading for the past few days, which was now sitting on the table in front of him. No... he was still too groggy from sleep.

He knew if he opened it now, he'd just end up reading the same sentences over and over without really absorbing much...

 _Not worth it, yet..._

 _Maybe after he'd had his coffee._

He turned his head a bit to glance into the living room.

Sherlock was sitting upright in his chair, his eyes closed and his face nearly expressionless. He'd been like that when John had come downstairs half an hour ago, and he hadn't moved yet, leading John to guess that he'd been in that exact position for quite a while.

Probably thinking.

 _About what...?_

The kettle clicked, and John turned his attention back to it.

It was very difficult to tell, with Sherlock.

It would have been easier to guess what he probably _wasn't_ thinking about.

Politics.

Sentiment.

Astronomy.

All very likely nowhere even _close_ to the detective's focus.

John sighed quietly and got up from where he was sitting to prepare the coffee, deciding to just go ahead and pour a cup for Sherlock, just in case.

"Black, no sugar."

The sudden, crisp sound of his voice made John nearly jump out of his skin, very lucky not to spill the boiling hot water on himself. He gripped the kettle's handle tighter and glared over at Sherlock.

"Jesus Christ— _don't_ —god, don't _DO THAT!_ It's too early..."

Sherlock just held him in that scrutinizing gaze, calm and almost quizzical.

John sucked in a deep breath, and tried to compose himself again, lips pressed together in a hard line. "Right. How long have you been awake?"

"Since Thursday."

"Yeah, okay, it's Saturday—let me rephrase... how long have you been... aware? You know what I mean. Responsive."

 _There was that quick smile..._

 _Smug..._

 _ **Annoying...**_

"Mm... ten minutes?" Sherlock shrugged.

"Thanks for letting me know..."

"Anytime."

"Yeah, that was sarcasm." John muttered, replacing the kettle and stirring his own cup of coffee.

"Figures..."

It didn't seem as if the detective was planning on getting up anytime soon, so after what John deemed a time sufficiently long enough to get on Sherlock's nerves, he finally grudged and brought his cup out into the living room for him.

Sherlock didn't bother looking up as he held out a hand for the cup.

But since he wasn't looking, he failed to catch the way John's eyes narrowed, or the way he paused, still holding the coffee.

"Sherlock."

The tone of John's voice seemed to catch his attention, and he raised his eyes to look at him questioningly.

"Sherlock..." John hesitated. "Why is your hand trembling?"

He followed John's gaze, as if just noticing it himself. "I... uh... probably just tired."

"Probably? No... you've stayed awake this long before without that happening..." John could already feel himself slipping into 'doctor mode,' though it was slightly overshadowed by 'concerned friend.' "Are you... are you okay?"


End file.
